Pulse jet mount



Oct. 7, 1952 w. L. TENNEY ETAL 2,512,748

PULSE JET MOUNT Filed April 6, 1946 s Sheds-Sheet 1 INVENTORSVV/LUAML.7E-'NNEY Y CHARLES tiMmeks Oct. 7., 1952 w. L. TENNEY EIALPULSE JET MOUNT 5 Sheets-Sheet 2 Filed April 6, 1946 ,GMMW

Oct. 7, 1952 w. TENNEY ETAL' PULSE JET MOUNT 3 Sheets-Sheet 3 FiledApril 6, 1946 INVENTORS Y M N L M m M w By CHARLES 15. MARKS UMQMW ATOEN YJ Patented Get. 7, 1952 PULSE jar MOUNT William L. Tenney,(Jrystal Bay, Minn, and

Charles B. Marks, Las Vegas',.Nev.; saidldarks' assignor to said TenneyApplication April 6, nus, Serial Iva-stairs This invention relates tojetpropulsion devices and more particularly to jet propulsion devices,mountings and shrouds therefor. In jet propulsion devices the combustionof fuel in the combustion chamber of the engine produces an exceedinglyhigh temperature which heats the combustion chamber and some or all ofthe exhaust pipe or pipes leading therefrom. As a result a veryconsiderable amount of heat'is radiated from the combustion chamber.Where the jet propulsion device is mounted in the open, the heat'that'isrejected from the surface of the combustion chamber and exhaust pipe orpipes does no harm other than the loss in efiiciency that is occasionedthereby, but in many applications it is desirable to mount the jetpropulsion device on or within a portion of the vehicle or unit beingpropelled, and the rejected heat thereby causesa heating hazard to thevehicle or propelled device unless suitable provision is made fordissipating the heat, bo'th'while the propelled device'is in motion andalso when the device has been stoppeda fter a hard and hot run.

It is an object of the present invention to provide a jetpropulsionunit, together with a mounting and shroud therefor, capable of providingfor safe housing of the unit on a prorx-illed vehicle or device withoutheat hazard to the propelled deviceor to theoperator of the device. Itis also an object of the invention to provide a more efilcient jetpropelling unitwherein the heat ordinarily rejected and dissipated fromthe combustion chamber and exhaust pipe or pipes is reclaimed at leastin part and converted into useful mechanical jet propulsion energy. Itis a further object of the invention to provide an improved jetpropulsion device particularly adapted for miniature or model vehicles,such as model airplanes, racing cars, boats and the like, and suitablefor mounting in vehicles constructed of materialswhichare inflammable orcapable of being deterioratedby heat. It is a further object of theinvention to provide as new articles of manufacture a combined jetpropulsion device shroud andmounting; an improved jet propulsion deviceshroud and mounting apparatus for miniature airplanesub-assemb1ies,inc1uding a portion of the miniatureairplane, such as thefuselage.

Other and further objects of the invention are 5 Claims. (:31. ac-est)those inherent in the apparatus herein illus- V 21 Figure '2 is'a frontelevational'view ofthe' appairatus shown in Figure 1; I

Figure 3 is a fragmentarysideelevational view of the front portion ofthe apparatus shown in Figure 1, including various auxiliaries;

Figures 4 5 and 6 are side elevational views;-

partly in section, illustrating,"respectively; three additional forms ofthe invention. Y

Throughout the drawings, corresponding numerals'refer to thes'am'e'p'a'rts.

Referring" to the-drawings, in Figures 1, 22nd 3 thereis provided a jetpropulsion device generally designated ic'havin'g a combustion chamber Hwhich is provided at its forward en'd'with v a forwardly taperedhousingI2 containing an 'in'l'et passage through which the inlet airand fuelmixture is adapted to be introduced into the combustion chamber. Thecombustion chamber'ha's a rearwardly tapered portion I3 which terminatesin an exhaust tube it of uniform cross sectional area which extends toand terminatesat the rear edge i5. The construction of the jetpropulsion device maybe of any desired type such'as that described inour copending application Ser'. No. 649,882, filed February 25, 1946,entitled Pulse Jet Engine, to which reference ishere made. Theconstruction of the jet unit l0, per se, forms 'no part of the presentinvention.

in operation the jet propulsion device 10 is intensely heated,particularly the rear portion of the jet combustion-chamber l I, thetapered sec tion it and'allor at least that part of the exhaust tube Hiadjacent the combustion chamber, and heat therefrom is ordinarilyrejected to the surrounding air-when the device is openly mounted. Theforward end of'the combustion chamber II, where it isjoined to the inletportion [2, is generaliy cool since the combustion air flowing throughthe inlet and the evaporation of the liquid fuel in the inlet tends tomaintain the temperature of these parts well below red heat. Inaccordance with the present invention the jet propulsion unit Wismounted withina mounting and shroud unit generally designated 20.

having an outer shell 2! that is attached to .a forward nose section 22so as to form an integral unit which is generally tapered at its forwardend 23 and its rearward end 24. The outer shape of unit 2c may be theshape of an airplane fuselage, model car body, wing section, or thelike,

' and may be aerodynamically streamlined. The

fiber," doped cloth, orany other suitable material capable ofwithstanding the stresses involved.

During use these portions of the apparatus are maintained at such a lowtemperature that no problem of deterioration due to heating isinvolvecl. The low temperature of operation of the outer shell 2l-22 isaccomplished by providing an insulating filler 26 which forms anenclosin shell around the jet propulsion device I!) but spaced therefromby an air space 28. The insulating filling is of the rigid type such asmolding asbestos, and abuts against the rear surface of the nose pieceas shown at 29 and completely fills the outer shell 2| and may be bondedthereto by any suitable cement along the surface 30. The insulation isshaped with a curve at 3| so as generally to conform to the curve of theforward section [2 of the jet propulsion unit, and thence is ofsubstantially uniform diameter at 32 opposite the portion ll of thecombustion zone. A somewhat increased space is provided at 33 in view ofthe intense heat radiation at this portion of the combustion chamber,and thence continues along the uniform diameter 34 to the rear portionof the unit and ends at the rear edge 36.

The jet propulsion unit is supported in spaced relationship tothe'interior aperture of the insulating filling 26 by means of a forwardmounting ring 38 and rear mounting ring 39. The forward mounting ring isattached to the combustion zone by a plurality of longitudinal fins 40between the combustion zone II and the ring. Twoor more fins may be usedso as to maintain the spacing of the propulsion unit at the forward end.Being oriented lengthwise of the unit, the fins do not appreciablyretard flow of cooling air-through space 28. The ring 38 is preferablyembedded into the insulating material 26, as indicated at 4|, so as toprevent longitudinal displacement of the jet device In with reference tothe insulation filled shell 20. At the rear end of the jet propulsionunit the mounting ring 38 extendsto the rear edge 36 and is likewisemaintained in spaced relationship to the exhaust tube l4 by two or morelongitudinal spacing fins 43. The portion 44 of the mounting ringoverhangs the rear edge I of the tube l4 and serves to protect thesomewhat fragile insulation filling 26 from the abrasive action of theexhaust gases as they issue from the propulsion device. The rearmounting ring 39 which supports the insulation filled shell 20 is notpermanently secured to the shell structure as is apparent from Figure 1.The exhaust tube l4 which is heated by the high temperature exhaustgases passing therethrough expands materially during the operation ofthe jet propulsion device I0. This provision for a slidable relationbetween the rear ring 39 and the insulated shell 20 supported thereonpermits longitudinal movement of the exhaust tube M with respect to theinsulated shell 20.

It will thus be seen that there is a clear channel as indicated by thearrows 45, 46, 41 and 48 permitting the flow of air around the body ofthe jet propulsion device I 0 when the device is in use. The exhaustgases issuing from the rear edge l5 of the exhaust tube, as indicated bythe arrows 49, serve to provide an ejector effect which maintains theflow of cooling air around the jet propu sion device l0 even while it isstationary. The flow around the jet propulsion device, as indicated byarrows 4548, is much intensified when the unit is moving through theair.

The jet propulsion device is provided with a fuel inlet tube 52 and astarting air inlet tube 53, as described in our aforementionedapplication Ser. No. 649,882. As indicated in Figures 2 and 3 a fueltank 54 may be mounted outside the housing 20 by a plurality of screwsindicated at 55. The fuel tank is provided with a fuel outlet pipe 56which is attached to the fuel inlet tube 52 by means of a short lengthof rubber tubing 51 when the device is in operation. The fuel tank islikewise provided with a filler plug which is normally closed by thescrew cap 58 and with an air inlet tube 59 that is directed in thedirection of motion of the unit and slightly belled out at its forwardend, as indicated at 60. When the entire jet propulsion device andhousing are moving through the atmosphere an air pressure is developedin tube 59 by air entering, as indicated by arrow Bi, and a positivepressure is therefore applied on the surface of the fuel within tank 54,thus enhancing the flow of fluid through line 56 to fuel inlet line 52.

The ignition device 62 of the jet propulsion device is provided with anignition wire 63 which simply passes out through the insulating filling28 and the outer shell 2|. Where the outer shell 2| or the filling 26are conductive, an insulating bushing, not illustrated, is providedaround the wire 63. For initiating operation of the device, an airpressure line is attached to the starting air inlet tube 53 and a hightension ignition wire attached to wire 63. The other ignition wire maybe attached to any metallic portion of the jet inlet device asindicated, for example, by wire 65 which is attached to the air inlethousing [2.

In operation the jet device is started and a large blast of exhaustgases emanates, as indicated by arrow 49, from the rear end l5 of theexhaust tube. The jet effect of these gases pulls additional cooling airaround the jet propulsion unit It] in the space inside the filling 26,as indicated by the arrows 4548. It has been found in operation that aconsiderable heating and, apparently, expansion of the cooling air takesplace during its passage around the jet propulsion device and that anadditional jet propulsion force is developed by the cooling airemanating at arrow 46. An additional thrust of as much as 15-20% hasthereby been obtained.

Referring to Figure 4 there is illustrated another form of the inventionwhere the construction is the same as shown in Figure 1 except that aliner 1!) is provided on the inner surface of the shell 20' so as toprotect the insulation filling 26. The inner surface of the insulation26 is accordingly prevented from disintegration due to vibration orabrasion caused by the flow of cooling air therethrough, and morefragile insulating materials, and insulating materials that areincapable of sustaining themselves, such as silica gel, exfoliatedvermiculite, magnesia fill, and even rock wool, may be used. In theconstruction shown in Figure 4 the lining I0 is preferably of metal ormay be a refractory coating, and the shells 10 and 20 are attached tothe nose section 23 by any suitable fastening. The shell 10 is suitablyrecessed at H so as to receive the forward mounting shroud 38, but therear mounting shroud may, in this instance, be narrowed as indicated at13 since the rear portion 14 of the inner shell 10 serves to provide thenecessary protection of the insulating'filling atthe rear end of theunit. The operation of the unit shown ilnaFigure 4 is the same as thatshown in Figures In Figure 5 there is illustrated another form of theinvention in which the jet propulsion device H) is of the same generalconstruction as previously described. .Ixi this-unit. howeverrthereinggair path 'along arrows 85,82 and 83, but also to preventsomeormostiof the heat from {passing outside of the shell M. In addition,v theouter mounting shell, as generally indicated :at 85 may likewise be ofmetal or may be composed of an inner shell 86 and an outer shell 81providing'an interior-space 88 that is fi-lled with heat insulation. Themounting of the unit Wis by'means of a plurality of longitudinal fins at90 and 9t. The'fins. till-"5D may, if desired, be attached to a mountingring 93 and in the event the shroud 8D is not of sufficiently/strongmaterial to stand the mounting forces, inner rings may be provided at94- and 95 so as to receive and serve as a mounting for the longitudinalfins 9 I. Amounting screw having a relatively large flat head isprovided at 9-6 and another at 9T. The. screws pass through the outershell 85 and the intervening shell 80 and are threaded-into the mountingring 93, thereby serving to maintain the jet propulsion unit Illcentrally located and the shell 80 in fixed spaced relationship withrespect to the unit Ill and 'theinterior surface of the shell 85. A-plura'lity of similar mounting fins and rings,,if desired, maybezprovided at-therear end of the unit, as indicated at 99 and Hill.Thespace between the intervening-shell 80 and the interior surface 85 ofthe outerunitte-provides' for the passage of air as indicated by thearrows H12, 403,, NM and ms. The-rear ring-$8 mounted on the-exhausttube in is not permanently secured to. the intervening shell 85) nor isthe ring Iilli so secured to the outer shell 85 as will be seen fromFigure 5.. Here, as in the form of the-invention shown in Figure 1,longitudinal movement of theexhaust tube i l with respect to theintervening shell. Bil is permitted; and, similarly, longitudinalmovement between the intervening shell 80 and the outer shell 35 mayoccur.

It will be noted that the rear end H36 ofthejet propulsion deviceterminates a short distance within; the rear end it? of the interveningshell 80, and the rear end ill-l of the-intervening shell likewiseterminatesa short distance. within the rear terminal edge Hill of theouter shroud 85. Ac cordingly, as exhaust gases issue from the jetpropulsion device as indicated by the arrow l ill, they produce a jeteffect and enhance the-movement of cooling air, as indicated by thearrows 83, and the combined movement of the exhaust-and cooling airgases, as indicated by the arrows H9 and 83 causes a further jet effectwhich facilitates the movement of air along the path defined by arrows lllft i llli. Heat dissipated by the jet propulsion device from thecombustion zone and adjacent portions of the exhaust pipe It causesconsiderable heat of the air; particularly'that portion. of thecoolingair-which passes along the path of arrows iii-83. Accordinglythese gases, and to some extent those shown at H35, are expanded andissue forth with a blast effect which increases the overall jet force ofthe unit as compared with the force produced by the jet propulsiondevice 89 when mounted in open air.

aforementioned, except that, the valve 'plateof the- In the devicesshown in :Figures l-5 the-iouter shell,: for example shell 281 ofFigure 1. or ill' o! Figures, and the intervening shellxto and outershell of Figure 5, are constructed-sons tobe longitudinally divided intotwo or morelongitudi nal sections. In the preferred "form the outershroud or shells are made in two halves, split lengthwise along the unitand are-heldintplace byany' suitable fastening, such as clips, bands,-orby portions of the vehicle orpropelled" :unit, of which the shell mayconstitute a part. If desired, however, the shell may be-made-sothat.the .jet unit Ill may be insertedifrom. the front end. Thus, "in thedevice shown in Figure' fi theouter shell generally-designated 121i .ispreferably :made

froma solidpiece'of refractory orheat insulating material, such asasbestos, C0lnpOSitiOl'l,-, foarrraceous cellular glass, or, the like,or several pieces that are permanently fastened together to .formtheshell. Thus, the shell I20 maybe turned-or bored from a solid blockofioarnaceouscellular glass (Foam Glass), magnesia, molded-asbestos orthe like, so as to have an outwardly tapered forward end iZi and alesser taperedwrearward"end I22. The interior of the shell has-a-=portiona of uniform diameter from the front end to the line I23 andthen tapers along a; straight line to a minimum diameter at the rearedge I 24. Thejet propulsion device ill is, in this.instance,..providedwith a mounting ring I25 sup-ported by two or more longitudinal spacers126. The ring is of :a diametersuch that it fits neatly into theinterior bore of the outer unit .520 and islfa-stene'd in place by twoor more screws [28 which pass through the unit 52% and are threaded intothe ring, 125. The rear mounting ring I38 istaperecl to fit the taperedrear interior surface l3l of the unit l Zll; Ring 53%). is likewisesupported by a; plurality of longitudinal spacing and supporting finsI33 "and iii. In fitting the units together, unitv Iii is pushedrearwardly into the shroud ii -2t until the tapered ring 38 fits neatlyinto the rear end of the unit 420 and screws 28 are then-set in'place soas to maintain the assembly. The rear over-- hanging portion 536 ofthe-ring, itdservesto'protest the interior surface of the outer shell1'20; it being noted that the rear edge i3 1 of'the jet-propulsion unitterminates slightly within the rear terminal edge 524 of the outer'shell If desired, the shell 28 may be 'coatedinsideandout with a smoothsurfacing material,. such. as a re fractory filler. Waterglassproduces'a smooth finish and is fairly refractoryand can therefore beused onthe inside of shell {28. Any desired fin ish'may bensedontheoutside ofoshell iii] asit does notget hot.

Thefollowing specific example illustrates but i's notinteri'ded to limitthe present'invention; This example showstheamount of additional.propelling force which maybe achieved by utilizing-the teachings of thepresent invention? The jet propulsionunit isof the typeset forthin ourcopending application 'Ser; No, 649,882,

inlet tube it of the. unit disclosed hereinhad'eight holes inch indiameter Whereas that in the unit discl'ose'd in the copendingapplicationhad 16 holes .25v inch in diameter. The combustion charnber'M a diameter Ora-5 inchesanda length oflL-Ziihches and thetaperedsection it had a length of 2.5 inches. The tail pipe l4 had adiameter of 1.375 inches and a length of 15 inches. The overhanginglength of the supporting ring I39 from the end I31 of the combustionchamber to the rear edge I 24 was 1 inch. The

7 interior-diameter of member I20 (Figure 6) was 3 inches to line I23and then tapered to a minimum diameter of 1.75 inches. Thus constructed,

the unit provided a jet propulsion force of 2.9-

pounds. When the jet propulsion device ID was removed from the shroudI20 and tested in open air, all other conditions being the same, the jetpropulsion force was 2.5 pounds, thus indicating a gain of .4 pound orapproximately 17% additional jet propulsion force due to the use of theshroud I20.

-As many apparently widely different embodiments of this invention maybe made without departing from the spirit and scope thereof, it is to beunderstood that we do not limit ourselves to the specific embodimentsherein except as defined by the appended claims.

What we claim is:

1. A jet propulsion device comprising a jet unit having a generallycylindrical combustion chamber, an air inlet in the front end of saidchamber and a generally tubular exhaust tube extending in a directionopposite from the inlet end thereof, a plurality of spacing membersmounted on said combustion chamber and extending outwardly therefrom, aplurality of spacing members supporting said exhaust tube adjacent theexhaust end thereof and extending outwardly therefrom, a generallytubular shell means surrounding said jet unit and being spaced therefromby said spacing members with said spacing members adjacent the exhaustend of said tube being disposed within said shell and forming a slidableconnection between said shell and said end of said tube, said shellmeans being open adjacent the inlet of said jet unit and open adjacentand extended beyond the exhaust tube and means for anchoring said shellmeans to said combustion chamber, said exhaust tube and said shell meansbeing free to move longitudinally with respect to each other adjacentthe exhaust end of said jet unit.

2. The apparatus of claim 1 further characterized in that said generallytubular shell means comprises an outer structural framework sheeting anda self-sustaining insulation therein, the inner surface of saidinsulation constituting the inner surface of said shell means.

3. The apparatus of claim 1 further characterized in that said generallytubular shell means comprises an outer structural framework sheeting, aninner structural framework sheet liner spaced therefrom and a fragileinsulating material supported by said outer and inner frameworks andfilling the space therebetween.

4. A jet propulsion device comprising a jet unit having a generallycylindrical combustion chamber, an air inlet in the front end of saidchamber and a generally tubular exhaust tube extending in a directionopposite from the inlet end thereof, a plurality of outwardly extendingspacing members mounted on said combustion chamber, a plurality ofoutwardly extending spacing members supporting said exhaust tubeadjacent the exhaust end thereon, a generally tubular shell meanssurrounding said jet unit and being spaced therefrom with said spacingmembers adjacent the exhaust end of said tube being disposed within saidshell and forming a slidable connection between said shell and said endof said-tube, said shell means being open adjacent the inlet of said jetunit and open adjacent and extended beyond the exhaust tube, meansmounted on said combustion chamber spacing members for supporting saidshell means. means mounted on said exhaust tube spacing members forsupporting said shell means, and means for anchoring said first namedshell supporting means to said shell to prevent longitudinaldisplacement between said shell means and said combustion chamber, saidexhaust tube and said shell means being free to move longitudinally withrespect to each other adjacent the exhaust end of said jet unit.

5. A jet propulsion device comprising a jet unit having a generallycylindrical combustion chamber, an air inlet in the front end of saidchamber and a generally tubular exhaust tube extending in a directionopposite from the inlet end thereof, a plurality of outwardly extendingspacing members mounted on said combustion chamber, a plurality ofoutwardly extending spacing members supporting said exhaust tubeadjacent the exhaust end thereof, a generally tubular shell meanssurrounding said jet unit and being spaced therefrom by said spacingmembers with said spacing members adjacent the exhaust end of said tubebeing disposed within said shell and forming a slidable connectionbetween said shell and said end of said tube, said shell means beingopen adjacent the inlet of said jet unit and open adjacent and extendedbeyond the end of said exhaust tube, means mounted on said combustionchamber spacing members for supporting said shell means and meansmounted on said exhaust tube spacing members for supporting said shellmeans, a plurality of outwardly extending spacing members mounted on theouter face of said shell means and being positioned over said combustionchamber spacing members, a plurality of outwardly extending spacingmembers mounted on the outer face of said shell means near the endthereof adjacent the exhaust end of said unit. an outer generallytubular shell means surrounding said first named shell means andbeingspaced therefrom by said spacing members mounted on the outer faceof said first named shell means, and means for anchoring said firstnamed and outer shells to said combustion chamber, said exhaust tube andsaid first named shell means being free to move longitudinally withrespect to each other adjacent the exhaust end of said unit and eachbeing free to move longitudinal ly with respect to said outer shellmeans.

WILLIAM L. TENNEY. CHARLES B. MARKS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,382,535 Offen June 21, 19211,611,353 Lepinte Dec. 21, 1926 2,074,098 Adams Mar. 16, 1937 2,237,329Bischof Apr. 8, 1941 2,404,954 Godsey July 30, 1946

